Problem/Condition

Arthralgia is pain within the joint. Arthritis is pain and inflammation of the joint. These terms are often used interchangeably for "joint pains". These should be differentiated from other pains involving the join such as tenosynovitis or bursitis.

A. What is the differential diagnosis for this problem?

The two clinical cues most helpful for diagnosis of joint pain are the joint pattern and the presence or absence of extra-articular manifestations.

Joint pattern is defined by three questions:

Start with the number of joints affected (some disease states are in multiple categories).

Careful examination of the knee for either a bulge sign or patellar ballottement, which are useful signs for effusion.

3. Laboratory, radiographic and other tests that are likely to be useful in diagnosing the cause of this problem

Initiation evaluation of acute joint symptoms should be done after a careful history and physical exam. Panels are not recommended as this increases the frequency of finding positive results unrelated to the disease.

Complete blood count (CBC), renal function, liver function, and urine tests should be ordered if a multisystem disease is suspected. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are markers of inflammation; CRP can be used to monitor response to treatment. If there is associated weakness and muscle pain then creatinine phosphokinase (CPK) should be ordered to evaluate for myositis.

Whenever possible a joint aspiration and examination of the joint fluid is essential to the diagnosis. Four elements help with this.

Clarity

Transparent fluid is typically non-inflammatory.

Translucent fluid is typically present with mild inflammation.

Opaque fluids are typically purulent.

Blood effusions are seen with trauma, bleeding disorders or traumatic taps.

WBC count of > 50,000 is specific for both infectious and inflammatory joint diseases.

Microscopic examination

Negatively birefringent: gout.

Positive birefringent: CPPD.

Gram stain can be highly specific for septic arthritis (100%) but its sensitivity is much less (45%).

Culture: aerobic and anaerobic cultures as well as special studies for gonococci, tuberculous or fungi as indicated. Consider sites to culture based on patient history.

Ordering chemistry studies of synovial fluid should be discouraged because they are likely to provide misleading or redundant information.

Other labs are indicated only if there is moderate suspicion for the following disease states as false positives are common:

RA - serum rheumatoid factor (RF)

SLE - antinuclear antibody (ANA) testing

Other testing such as human leukocyte antigen-B27 (HLA-B27) (ankylosing spondylitis), antineutrophil cytoplasmic antibodies (ANCA) (Wegner's), Lyme serologies, parvovirus serologies, anti-Jo-1 antibody (inflammatory myositis), and antiphospholipid antibodies are only useful when there is high clinical suspicion for these disease processes.

C. Criteria for Diagnosing Each Diagnosis in the Method Above.

See above.

D. Over-utilized or “wasted” diagnostic tests associated with the evaluation of this problem.

Imaging studies are indicated when the exam cannot localize the structure causing the symptoms. This would be mostly after significant trauma, loss of joint function, fracture, bone infection, or when malignancy is expected. Plain radiographs are often unrevealing or unhelpful for most patients with acute and new symptoms.

A. Management of joint pain.

With regards to the management of joint pain the first question you often ask is if this is a septic joint or not?

Septic joints are a medical emergency with high risk of morbidity and mortality, and require appropriate antibiotic therapy and early orthopedic consultation for drainage, lavage, and debridement.

If the causative organism cannot be determined clinically or from gram stain, treatment should be initiated with broad-spectrum antibiotics that cover Staphylococci MRSA, Streptococci, and gram-negative organisms.

The typical starting regimen for non-gonococcal septic arthritis is Vancomycin and a third-generation cephalopsorin.

For gonnococcal arthiritis the treatment regiment is Azithromycin (1 g orally as a single dose) and a third-generation cephalosporin: ceftriaxone, 1 g intravenously daily (or every 12 hours if concomitant meningitis or endocarditis is suspected); or cefotaxime, 1 g intravenously every 8 hours; or ceftizoxime, 1 g intravenously every 8 hours.

Antibiotic coverage should then be adjusted once culture results become available, and continued for 6 weeks.

Remember, WBC count of > 50,000 is specific for both infectious and inflammatory joint diseases.

If the joint is not septic then management typically involves determining the diagnosis and proceeding with treatment, which often occurs in the outpatient setting and with the help of a specialist, often a rheumatologist.

B. Common Pitfalls and Side-Effects of Management of this Clinical Problem

The most useful information in evaluating musculoskeletal pain comes from the history and physical examination, with reassessment as necessary. When the diagnosis and proper management are obscure, selective ordering of tests may be the most cost-effective approach.

Joint pains are commonly managed initially with high-dose non-steroidal anti-inflammatory drugs (NSAIDS). Common contraindications to NSAIDS that may be overlooked are chronic kidney disease, congestive heart failure and history of a bleeding ulcer.